Development of GaAs Detectors for Ionising Radiation

This thesis presents an account of the development of particle detectors made on gallium arsenide semiconductor material. The state of the art in semiconductor detectors is reviewed and likely requirements for the future at LHC outlined. Fabrication of devices is described, as is their characterisation and testing in the laboratory. Less than full charge collection efficiency for devices fabricated on semi-insulating material has been explained in terms of a limited sensitive thickness. Reverse-bias leakage currents appear to be due to generation of carriers at surface states. The performance of materials grown by different processes is compared. Detectors have been tested in particle beams at CERN and analysis of test beam data is presented for single-sided devices and a double-sided device. The radiation hardness of the detectors is examined with reference to LHC requirements